<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        var num1 = 100;
        var num2 = 200;
        var x;
        // console.log(num1 + 1)
        // console.log(num2 + 2)
        //自增
        // console.log(num1++)
        // console.log(++num1)
        //x=num1++
        // console.log(x)
        // console.log(num1)
        //x=++num1

        // console.log(x)
        // console.log(num1)

        //按值传递

        var x = num1
        num1 = 1000

        console.log(x)
    </script>
</body>

</html>